Core bit



I. H. BULLOCK May 2, 1950 CORE BIT Filed Oct. 28, 1948 INVENTOR.

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COR-E BIT Ian Herbert Bullock, Detroit, Mich, assignor to Koebel DiamondTool 00., Detroit, Mich., a. corporation of Michigan Application October28, 1948, SerialNo. 57,063

2 Claims.

This invention relates to drill bits or similar tools useful, forexample, in drilling into hard earth strata, such as packed orconsolidated sand, rock formations, sandstone and the like. Theinvention is especially applicable to drilling tools commonly known ascore bits which are employed widely in coring operations when drillingfor oil or for other purposes where it is desired, for example, to makesoundings in order to obtain specimens of earth formations forgeological analysis.

Core bits employed in coring wells are frequently equipped with diamondsin order to increase the drilling rate and prolong the life of the bits.In the case of diamond core bits the diamonds are usually set in amatrix formed, for example, of sintered powdered or comminuted metal.This matrix or slug is permanently secured as by brazing to the body ofthe core bit which in turn is threaded for attachment to the corebarrel. Since the core bits are subjected to extremely hard usage, wearand shocks during the drilling operations, the cutting portions thereofoften become fractured, chipped, broken or otherwise damaged, making itusually necessary to replace the entire core bit. The damaged core bitcan seldom be usefully repaired after being withdrawn from the well orhole being cored out. Hence, the bit is usually scrapped, even thoughonly a portion thereof is damaged and the remainder is in usefulcondition. The relatively high cost of the core bits, especially diamondcore bits, greatly increases the cost of drilling operationsas a resultof the necessity of scrapping the entire core bit whenever damagethereto of such nature occurs as to render the bit inoperative orineffectual for eflicient coring work.

One of the chief objects of the invention is to overcome the foregoingdisadvantages by providing a bit which is not only efiicient in carryingout the work required of it but which may be readily repaired or renewedas to usefulness when only partially damaged or worn.

Another important object of the present invention is to provide a drillbit of improved construction having cutting portions or members whichmay be removed and replaced, thereby prolonging the life of the bit as awhole, reducing greatly the overall cost thereof, and as a consequencereducing the cost of drilling operations;

A further object of the invention is to provide a core bit having atubular body adapted at one end to receive a plurality of drill membersdetachably mounted thereto, said body having a threaded extension at itsopposite end for at- 2 tachment to a tubular adaptor which in turn isattachable to the end of a core barrel, there being an annular shoulderon the body at the base of said threaded extension which is covered oroverlapped by a portion of the adaptor, and the attaching means for thedrill members in.- cluding threaded devices extending througha portionof the body and accessible for operation at said shoulder when the corebit is detached from the adaptor.

Another object of the invention is to provide a core bit comprising anannular body having radial slots or recesses for the reception of drillinserts and means or devices for firmly and rigidly clamping the insertsin position against dislodgement during operation, said drill insertsand clamping devices being preferably removable and replaceable in orderto prolong the life of the core bit.

Other and more specific objects of the invention are to provide a corebit of the foregoing character and having improved means for detachablysecuring the clamping devices to the core bit body whereby said securingmeans are shielded from the abrasive action of the drilling operation;to provide such a core bit wherein the clamping means for the detachableinserts include screw threaded bolt means having their heads protectedwithin the body of the core bit and accessible from the end thereofwhich is connected to the core barrel upon detachment of the latter fromthe core bit; and to provide such a core bit which is removablyconnected to the core barrel by an adaptor means, whereby operativeportions of the securing means for the detachable drill inserts, whicheffect the detachable securing engagement between the securing means andthe drill inserts, are shielded by the adaptor when the latter is inoperative position with the core bit, and whereby attachment betweencore bits and core barrels of various sizes and types is also permitted.

Still another object is to provide a drill construction of the characterdescribed which is of simplified construction and design, therebyachieving optimum economy in manufacture and maintenance and permittingrepairs and replace; ment of parts with a minimum of expense and losttime.

Other objects of this invention Will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

Fig. 1 is a fragmentary axial section showing a core bit and adaptorembodying the present invention and installed on the lower end of a corebarrel.

Fig. 2 is a fragmentary enlarged bottom view of the core bit shown inFig. 1.

Fig. 3 is a fragmentary enlarged axial section taken substantially inthe direction of the radial arrows along the circumferential line 3-3 ofFig. 2.

Before explaining the present invention in detail it is to be understoodthat the invention is not limited in its application to the details ofconstruction and arrangement of parts illustrated in the accompanyingdrawings, since the invention is capable of other embodiments and ofbeing practiced or carried out in various ways. Also it is to beunderstood that the phraseology or terminology employed herein is forthe purpose of description and not of limitation.

A preferred'emb'odiment'of the present inven- "tionis illustrated by wayof example in application with a core bit, preferably of the diamondtype, wherein the cutting or drill elements are mo'un'ted around thelower end of an annular or tubular supporting body which in turn isdetachably'connected to the lower end of the usual core fib'arrel bymeans of a concentric annular adaptor. During a drilling operation, thecore barrel with the attached adaptor and bit are rotated about"their-longitudinal axis at a suitable speed, such "as between 100 R. P.M. and 150 R. P. 'M. The bore bit cuts a generally circular hole and atthe same time separates from the earth a central core which is forcedupwardly through the bit and barrel as the drilling operation proceeds.

It is important that the core bit be made rugged and strong so as toenable the same to cut the maximum possible depth before replacementbecomes necessary due to wear, and further that the construction ofthebit be such as to ensure the romation of an unbroken core. Heretofore,it has been the practice to secure the core bit cutting elementspermanently and solidly to the 'bod'y' of'th'e bit, as'by brazing,thereby to assure the-production of a bit having the greatestpossible-strength. As pointed out above, such a constructionprecludesrepair of the bit ina great many instances where damage to the bit hasbeen xinly' -o f a partial nature. In accordance with the 'prsentinventionthe drillor cutting elements bf *the bit are made separablefrom the body, yet means are provided of such character as to enable thecutting elements to be so rigidly wedged-or clamped to the body 'astoirender the structure effect substantially a solid unit having as higha degree of strength and ruggedness "as heretofore.

"Referring to the drawings, the core bit therein shown comprises anannular body provided with-an annular interior shoulder 22 extendingfrom the base of an interiorly threaded extension' 24. This extension isadapted to be screwed into an exteriorly threaded portion 26 of acylintlr'ical adaptor indicated generally by the numeral '28. "Theadaptor 28 is provided with an annular "shoulder 30, adapted to overliethe upper threaded an '24- of the core bit, and also is provided'with areduced exteriorly tapped upper portion 32 adapted to be threaded-intothe lower tapped end ore-conventional core barrel 34.

I "Aslllustrated in Fig. 1, the adaptor 28 is formed With-an internaltaperingwall 36 which converges axially toward the lower end of the body20 of the core bit assembly. accordance with usual practice, there ismounted during use within the adaptor 2a a tapered split ring known as acore catcher (not shown) which is provided with a number of internalribs or dogs adapted to grab the core when the split ring is pusheddownwardly into the tapered interior wall 36. It will be understood thatduring the coring operation. the core slides freely through the corecatcher, but when the core bit assembly is pulled off bottom or drawnupwardly, the core catcher is forced down into the tapered Wall 33causing the aforesaid ribs or dogs to tighten around the core.

At the base of the screw threaded portion 26, the body of the adaptor 28provides an external annular shoulder 38 which is adapted to seattightly against the shoulder 22 of the core bit when the latter isscrewed in the operative position on the adaptor 28. Likewise, in theassembled position, the base of the tapered wall 36 extends below theshoulder 22 and rests on an annular shoulder 4S provided interiorly onthe core bit body 23. Thus, for a purpose which will be 'made'apparentbelow, when the adaptor '23 and'core bit 2i! are assembled, thesidewalls thereof cooperate to enclose the interior shoulder 22 andshield the same from dirt and abrasion that would otherwise result froma'drilling operation.

The body of the core bit 2t terminates below the tapered inner 'wall 35in an annular opening and is machined at its lower annular edge toprovide a'number of equally spaced radially extending slots' l2 for thereceptionof a corresponding number of drill inserts 'or cutting elements44. Each insert i l 'may be formed from a matrix of sintered powdered orcomminuted metal alloy having a number of protruding diamondsfi'set inthe outer-surface thereof in accordance with conventional practice.Although only a fewprotruding diamonds 46 are shown for each insert 44,it will be understood'that'this merelyfor illustration, since a largenumber-of diamonds 46 are ordinarily set in the face of each drillinsert to provide the required cutting surface.

Each drill-insert le is formed in the present instance with an upperheadportion chamfered at 48 atthe interior and 'exterioredges and havingparallel axially extending side surfaces "50 corresponding in depthsubstantially to the depth of the slots 42 and dimensioned so as to fitsnug- 1y thereinto. Starting from the base of the head of each insert44, the sides are tapered at 52 so as to converge downwardly, each sidebeingpreferably formed on a taper of approximately five degrees. Thecutting face 54 of 'eachinsert'M is generally arcuatein shape in aradial :direction at its lower end'and isgenerally vertical-at the-innerand outer upper edges. The-head of each insert is machinedtoi-provide :acentral transverse or circumferentially extending slot -or keyway 53having parallel rectangular-sides, Figs. 1 and 3.

Also as illustrated in Figs. 1 and :3,'the .body 20 is drilled axiallythrough the baseof each :slot 42 to provide a cylindrical hole Sli'forthe reception of the shank of a dowel pin or'adjusting stud 60 which hasaslip fit within the hole 53. The pin or'stud Bil terminates in-ahexagon head- 62, Fig. 2, dimensioned to fit'snugly within the slot 56.Since the shank of the pin or stud'fill- 'has a snug fit within the-hole 58,it is desirable to "machine an airbleed groove 56- in' thelength of the pin 60.

From the foregoing it will be' seen that each drill insert-or cuttingelement hasa rectangular sided upper head portion adaptedtofitsnugly inany one of the radial slots 42 in the body 26 and has a transversekeywayor slot 56 at its upper end within which the hexagon head 62 of the pin66 is keyed. The slot 56 does not key the head 62 against movementlengthwise of the slot 56, i. e. circumferentially. However, by virtueof the snug fit of the head 62 within the slot 56, displacement of thedrill insert 44 in a radial direction is prevented.

The several drill inserts 44 are rigidly held. in position on the lowerend of the core bit body 26 by means of a corresponding number ofclamping devices 66, each being wedged shaped in two directions.Referring to the drawings, it will be seen that each clamp 66'has a flatupper face 68, Fig. l, and tapering side walls 16 which diverge downwardand radially outward.

Corresponding to the taper of the side wall 52 of the drill insert 44,the taper of each side wall 16 is also preferably approximately fivdegrees. I prefer to use a taper 'of five degrees but not exceedingseven degrees so that when the clamp 66 is driven or wedged in betweenadjacent drill inserts 44, the engagement of the corresponding taperedsurfaces of the clamp and inserts will be of a binding nature preventingany tendency of the clamps 66 or inserts 44 to loosen during operation.

Each clamp 66 terminates downwardly in a generally arcuate edge 12 andis provided with a concave relief 14 extending between the edges 12 fromthe inner end to the outer end. It will be noted that the lower ends ofthe drill inserts 44 protrude well below the lower marginal edges 12 ofthe clamp 66. By relieving the faces of the clamps at 14, water coursesof substantial depth are provided between adjacent drill inserts.Similar vertical grooved water courses (not shown) may be spacedcircumferentially around the lower outer periphery of the core bit 26,if desired, so as to communicate with the grooves 14. Thus water orother liquid pumped down the core barrel 34, adaptor 28 and core bit 26may flow outwardly through these water courses.

As illustrated in Fig. 1 an annular groove or step 16 is machined aroundthe inner portion of the end face of the body 26, thereby providing acontinuous annular shoulder 18 adapted to abut the heel 86 whichprojects upwardly from the inner or narrow end of the clamp 66 when thelatter is installed in its clamping position. Thus positive means areprovided to prevent radial outward displacement of the clamp 66. Inaddition, each clamp 66 is secured in position by means of a screw 82having a threaded shank and terminating at its upper end in a head 84within the counter bore 86 which extends axially downward from theshoulder 22 into the body 26. A hole 88 of reduced diameter is boredaxially through the body 26 from the base of the counter bore 86,leaving at the base of the latter a shoulder portion engaged by the head84 to prevent the same from passing through the hole 88. The lower endof the hole 88 is adapted to align with a tapped hole 96 extendingaxially into the clamp 66 from the upper plane surface 68 and into whichthe shank of the screw 82 is screwed.

Prior to mounting the core bit 26 on the adaptor 28, the screws 82 areinserted into their corresponding counterbores 86, with each threadedshank projecting from the body 26 so as to be threaded into the tappedhole 96 therefor within the respective clamp 66. When the inserts 44 areinterposed between the clamps 66, the latter are drawn tightly againstthe body 26 of the core bit by tightening the screws 82. Thus the clamps66 and inserts 44 are rigidly locked to the body 26 by virtue of theinterengagementv of the tapered walls 12 and 16. Sufficient clearance 62is allowed between the upper surfaces of the clamps 66 and the adjacentunder surfaces of the core bit body 26 to ensure drawing of the clamps66 upward to a maximum depth permitted by the drill inserts 44 upontightening the screws 82.

In the illustrated embodiment the drill inserts 44 are preferablyadjustable radially so as to compensate for wear occurring during thedrilling operation. This is accomplished by forming the hexagonal head62 asymmetrically with respect'to the axis of the shaft of the stud 66,enabling the latter to be turned to any one of six indexed posi-. tionsso as to dispose the insert 44 in a desired radial position with respectto the body 26. Ad-.- justment of the drill inserts 44 maybe-accomplished by unscrewing the core bit body 26 from the adaptor 28and thereafter removing the clamps 66 at opposite sides of the insert44.- The latter is then removed to permit the stud or dowel pin 66 to beturned to the desired position of adjustment, after which the parts areassembled in the manner shown in the drawings. Since the radialadjusting means for the drill inserts forms no part of the presentinvention, a further description thereof is deemed unnecessary, the:same being shown and described in a copending application Ser. No.788,754.

With the drill inserts 44 rigidly clamped in assembled relation by meansof the clamping devices 66, it will be seen that each drill insert 44will be held in fixed position against any possibility of displacementin any direction. The insert 44 is held within its slot 42 againstcircumferential displacement. Engagement of the tapering side walls 52of the drill insert 44 with the corresponding side walls 16 of the clamp66, in conjunction with the screws 82, prevents axial displacement ofthe inserts 44. Engagement of the heel 86 on each clamp 66 with theabutment shoulder 18 will prevent outward radial displacement of theclamp 66, thus relieving the shear load on the screw 82. Displacement ofthe drill inserts 44 in either radial direction is also blocked by thehead 62 keyed within the slot 56.

By the structure described, it is apparent that the drill inserts 44 aredetachably secured to the body 26 by securing means (including theclamps 66) having operative portions or means, i. e. the screws 82 inthe present instance, extending through the body 26 and being accessibleat the upper portions of the latter to permit selective tightening orloosening of the clamping engagement between the clamps 66 and inserts44. In this connection, it is to be observed that the lower ends of theaforesaid operative means or screws 82 preferably do not project belowthe recessed faces 14 of the clamping members 66. The heads 84 of thescrews 82 may be of the socket type so as to receive an Allen typewrench, for example, and are protected by the cooperating wall portionsof the assembled body 26 and adaptor 28 during the drilling operationagainst abrasion and deformation which would otherwise render removal ofthe inserts 44 difficult. Further, by virtue of the adaptor 28, anoperative connection between core bits and core barrels of various sizesand types is readily permitted.

Although the embodiment of the present invention described 'by way ofexample herein employs.

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a. clamp type. securing means: havin the screw typez openatiizez. means.82- for selectively lighten, on loosening: the; clamps lite from: theinserts 45 it: apparent; that other types of? securing means-maybeemployed within. the spirit of the present invention for detachablysecuring; a pluralityef. drill: inserts ato; as. core bit body and;have-7 ing' other. operating: means. accessibleat theshieldediport-ionsoi thevbody 2E1; uponllooseningon removing:theeadapton ZB for; selectively effect:- ing the securing engagementwith the: drill inserts.

1:. claim;

ls Iniapcore bitgthe combination of. a2 tubulan body-l adapted:toxreceivealplurality of drill membersdetachably mountable thereto at:one end; means for: detachably connecting said. body to a; core barrel;and: including an. adaptcn detachablyconnected to said: body at thebtherend: of? the latten, saidibody having portions adapted tobesubstantially covered by said adaptor when the.-

latter is operatively connected to said may clamping devices: engageablewith said members forrdetachably clamping the same tosaid: body,andiscrew threaded meansengaged' with sai'cl d'evicesiorreleasablydrawing thesame toward said:

upon being: tightened and being extendedfrom" said devices-through saidbody 00- saidportions to: permit tightening or' loosening: thereat. In wcore bit; the combination of a tubular body adapted toreceivea pluralityoidri1l-'mem'-- hers detachamy mounted; annui'arly' on, one: endthereof; means for: deta'chably connecting said body; withaicore-barizel-and; including adaptor detachably seoureda to SEtidibOdyat: the-.othenend thereof, annularlydisposed, interior: shoulderportions 011 said; body; cooperating w'alli portions of said; body andadapter for enclosing said shoulder portionswhen said. body and: adaptorare operatively" secured. clamping. devices: engage;- able with saiddrill members? for detachablyf clamping: the: latter to: said body; andscrew threaded means: engagedwith said devices. for releasably drawingthe: latter: toward: said body in clamping; engagement; with; saidmembers and being; extendedlthrough saidlbody to:sa=i'd shoulderportions to; be; tightened; or; loosened thereati IANHERBERTBUILO'CK;

REFERENGE'S- ("ll-T1531) The, following references. are of rec-lord in.the file, of this patent;

UNITED: STATES, PATENTS;-

Number- Name Hete- 1,224,509* Smith' May" 1; 1917 1,468,774 CaldwellSept. 25"; 19 23 1,519,641 Thompson Dec; 16} 1924 1 ,542,172 Reed et a1.June 16; 1925 2,182,562 Koebel Dec. 5; 1939 23263908 Williams Aug; 1'7,1943

